River Map Ho-T'u and Magic Square Lo-Shu of Early China (revised and illustrated version)
A Neolithic calendar sanctuary on the Ordos Plateau?
The central part of the modified River Map could have served as a Neolithic calendar sanctuary on the northern (northwestern) part of the Ordos Plateau (geographical latitude around 40 degrees, perhaps nine thousand years ago). A circle of ten poles would have allowed to predict sunrises and sunsets on the solstices (and equinoxes), a flat horizon and a numerical model of the year provided. The rhomb is given by the sighting lines of the solstices. (Numbers of the drawing: middle radius 34, middle diameter 68, outer diameter 72, inner diameter 64, diameter pole 4, long axis 2 x 55 = 110, short axis 2 x 40 = 80, side of rhomb 13 21 21 13 sum 68.) The morning sun of the spring equinox just rose over the eastern horizon (tiny yellow circle on the right side) http://www.seshat.ch/home/china07.GIF
If you go to Google Maps and zoom down on Ordos you'll see a wide plaza with a large sun emitting long rays, along the circumference twenty flares or protuberances, twice the number of the ten poles on a circle in the hypothetical Neolithic calendar sanctuary.
A large bronze drum from Dong Son, Vietnam, 3rd century BC (Paris, Musé Guimet) shows a star of fourteen points in the center, suggesting a calendar sanctuary of 14 poles on a circle, going along with the geographical latitude of Vietnam and their angle of the sighting lines of the rising and setting sun on the solstices. 14 periods of 26 days are 364 days, add 1 and occasionally 2 days and you get a regular year of 365 days and an occasional leap year of 366 days. 92 periods of 26 days are 2392 days for 81 lunations, or 17 15 17 15 17 15 17 lunations, each period counted in the Stone Age way, 30 29 30 29 30 29 30 ... days, yielding 443 days for 17 and 502 days for 17 lunations. Mistake per lunation less than half a minute, or a quarter day in a lifetime.